Not Applicable
Not Applicable
Not Applicable
The invention relates to an intake manifold for a six-cylinder in-line internal combustion engine, in particular a manifold that provides for a single plenum and long individual intake runners in a compact unit.
Intake manifolds of internal combustion engines transport combustion air or a combustible air/fuel mixture to the cylinders of the engine. A carburetor or other type of air control valve typically mounts over the plenum of the manifold. Air enters the plenum through the air controlling valve and travels to the individual cylinders in individual ducts that are commonly referred to as runners. It has been shown that as runner length increases there is a positive effect on engine performance. This is due to a more consistent airflow at the intake port as a result of the inertia energy created as the air or air/fuel mixture travels toward the engines intake valves, and is commonly referred to as inertia charging. Although there are diminishing returns on increasing runner length, the limited space under-hood of an automobile is the usual factor in determining the practical length of intake runners. It is therefore of great importance to make a manifold that provides the benefit of long runners in a compact arrangement. In addition to length and compactness parameters, a useful manifold should be as simple in construction as possible in order to be economical to produce.
Accomplishing a compact, long runner manifold for a six-cylinder in-line engine presents a greater challenge than a four-cylinder in-line engine or a V shaped engine of six or eight cylinders. This is due to the greater overall length of the six cylinder in-line engine, which puts the air controlling device significantly closer to some intake ports than others when the air controlling valve is mounted in close proximity to the engine.
An overview of the prior art and their corresponding shortcomings can be roughly divided into three categories, as follows:
Category One; using a long or large volume plenum (xe2x80x9csurge tankxe2x80x9d) to make up the air control valve-to-runner distance differential. Examples would be U.S. Pat. Nos. 1,942,226, 3,945,357, 4,515,115, 4,664,075, 4,719,879, 4,867,110, and 5,642,698.
A long or large plenum contains slow moving air, thus taking up limited under-hood space without contributing to the highly desired inertia charging that only long runners can produce. Manifolds with a large or long plenum downstream of an air/fuel mixing device are vulnerable to fuel suspension problems such as wall wetting, pooling, and condensation. In addition, runners that begin furthest downstream of the manifold""s air inlet can become starved for air under high engine loads, compared to runners that begin nearest the air inlet in manifolds with a long or large plenum.
Category Two; woven-tube configurations. Examples would be U.S. Pat. Nos. 2,862,490, 4,228,769, 4,341,186, 4,409,934, 5,074,258, 5,144,918, and 6,283,078.
Woven-tube manifolds are excessively heavy and voluminous for the runner length they provide due to the paths they must travel to avoid running into each other, their inability to share common walls, their usually round shape, and the need of the runners to be traveling in many different planes in order to provide sufficient runner length. The multi-plane dimensionality of these manifolds makes them rather difficult and expensive to produce by the sand-cast methods normally used to produce metal manifolds. Woven-tube style manifolds use runners with round internal cross-sections which then change to a generally rectangular shape at the intake port, thereby creating turbulence and reducing the desired inertia charging effect.
Category Three; highly meandered or labyrinth configurations. Examples would be U.S. Pat. Nos. 5,655,492, and 5,704,325.
Meandered or labyrinth manifolds create theoretically long runners in very compact dimensions, but the high number of changes in flow direction creates turbulence that leads to large inertia losses and significant fuel suspension problems.
The object of the invention is to produce an intake manifold for six-cylinder in-line engines with the benefits of compactness, light weight, inertia charging, good fuel suspension properties, and ease of manufacture by traditional metal-casting methods. A further object of this invention is to produce an intake manifold that has the above mentioned benefits and can be retrofitted quickly and easily to many previously manufactured six-cylinder in-line engines. Said previously manufactured engines being originally equipped with a much less effective manifold, said manifold having a centrally mounted carburetor and a substantially single plane design.
The present invention provides for a compact manifold wherein the plenum is generally centered longitudinally, and the runners and plenum are aligned substantially upon the same imaginary plane.
The present invention provides for a compact and lightweight manifold by the use of runners that are generally rectangular in shape, thereby allowing the significant advantage of shared walls between runners.
The present invention provides for a manifold wherein all six intake runners begin substantially equidistant from the air control valve, thus providing substantially equal flow in all runners under all engine loads.
The present invention provides for a manifold with the advantages of small plenum volume due to the arrangement of the runner openings, which begin close to and substantially equidistant from the air control valve.
The present invention provides for inertia charging as a result of uniform and significant individual runner length.
The present invention provides for efficient, non-turbulent flow from the manifold runners into the engine intake ports due to the similarly rectangular shapes of the runners and the engine intake ports.
The present invention provides for an improved manifold that is easily interchanged with less beneficial manifolds on previously produced engines by virtue of a single-plane arrangement and a centrally located plenum.
The present invention provides for ease of manufacture by traditional metal casting processes as a result of shared runner walls and single-plane design.
The present invention provides for good dissolved-fuel suspension properties as a result of small plenum volume and runners that have no more than two turns of flow direction in any one runner.